Transcriptome analysis provides preliminary insights into the response of Sepia esculenta to high salinity stress

Sepia esculenta is an economically important cephalopod species contributing to aquaculture in China. Global climate changes have increased fluctuations in the ocean salinity level, which is a major problem for S. esculenta populations because extreme changes in salinity may be fatal to marine life. In this study, S. esculenta larvae were subjected to high salinity stress to investigate their stress resistance mechanisms. High-throughput transcriptome sequencing technology was used to detect transcript-level changes in samples. A total of 1126 significant differentially expressed genes were identified. The results of functional enrichment analyses showed that high salinity activated apoptosis and several innate immunity-related pathways in S. esculenta larvae. On the basis of a protein–protein interaction network analysis, PARP1, PIK3CB and FLNA were identified as hub genes involved in larval resistance to high salinity. Quantitative real-time PCR technology was used to analyze gene expression and verify the accuracy of the transcriptome sequencing results. The process of apoptosis can restrict high salinity-induced tissue damage, while the activation of an inflammatory response can maintain cellular homeostasis. Therefore, we speculate that high salinity induces innate immunity and apoptosis in S. esculenta larvae and modulates growth and development. These findings also suggest that aquaculture losses due to increased seawater salinity must be prevented in artificial aquaculture systems.